Determination of organic acids in the presence of inorganic anions by ion chromatography with suppressed conductivity detection

Simultaneous separation of 19 organic acids and 10 inorganic anions has been demonstrated using ion chromatography with a high capacity anion exchange column and the suppressed conductivity detector under an auto-suppression external sulfuric acid mode. Quantitative merits of this method were examined for analysis of nine organic acids of potential significance in cell culture broth. External calibration curves for these analytes were linear with correlation coefficients exceeding 0.999, and the relative standard derivations of observed analyte concentrations were less than 3.0% in both inter- and intra-day evaluations of aqueous standards. Developed methodology was subsequently applied to obtain organic acid profiles of Luria-Bertani liquid media, yeast extract, peptone, and the culture broth of a mutant Escherichia coli strain. Analytes recoveries observed for triplicate analysis of LB media spiked at two concentration levels ranged from 88% to 105% with less than 7% RSD. These data demonstrate quantitative accuracy for LB media and suggest that the report method may also be applicable to complex samples such as fermentation mixture and lignocellulose hydrolysate.